Recently, a Multiple Input Multiple Output (MIMO) system has been a focus of attention as broadband wireless mobile communication technology. The MIMO system can increase spectral efficiency in proportion to the number of antennas, compared with a conventional Single Input Single Output (SISO) system.
MIMO is multiple antenna technology which establishes high-rate communication using a plurality of transmission antennas and a plurality of reception antennas. The MIMO technology may be divided into a spatial multiplexing scheme and a spatial diversity scheme, depending on whether or not data transmitted through the antennas is the same.
The spatial multiplexing scheme refers to a scheme for simultaneously transmitting different data through several transmission antennas. A transmitter transmits different data through each transmission antenna and a receiver identifies several pieces of transmitted data through adequate interference removal and signal processing. Accordingly, data transfer rate can be improved in proportion to the number of transmission antennas.
The spatial diversity scheme refers to a scheme for transmitting the same data through several transmission antennas so as to obtain transmission diversity gain. The spatial diversity scheme is one of space-time channel coding schemes. The spatial diversity scheme does not increase transfer rate, but increases transmission reliability.
In addition, MIMO technology is divided into an open-loop scheme (e.g., BLAST, STTC, etc.) and a closed-loop scheme (e.g., TxAA, etc.), depending on whether feedback information of a channel status is transmitted from a receiver to a transmitter.
A collaborative MIMO system is proposed in order to reduce inter-cell interference in a multi-cell environment. If a collaborative MIMO system is used, a terminal may collaboratively receive data from a multi-cell base station. That is, communication performance of a terminal in a cell boundary can be improved using collaborative MIMO in a multi-cell environment. Research has been conducted into a method for transmitting and receiving data using collaborative MIMO. In particular, research has been conducted into a method for performing multi-cell MIMO while maintaining compatibility with a conventional single-cell MIMO system.